1. Field of the Invention
The present invention pertains to improvements in surgical cutting instruments. The invention has particular utility in connection with surgical cutting instruments of the type described in copending application Ser. No. 08/422,049 now pending assigned to the coon assignee, and will be described in connection with such utility, although other utilities are contemplated.
2. Background
The use of elongated surgical cutting instruments has become well accepted in performing closed surgery, such as orthoscopic or, more generally, endoscopic surgery. As described in U.S. Pat. No. 5,061,238, in closed surgery, access to the surgical site is gained via one or more portals, and instruments used in the surgical procedure must be elongated to permit the distal ends of the instruments to reach a desired location in a patient. Surgical cutting instruments for use in closed surgery conventionally have an elongated outer tubular member terminating at a distal end having an opening in a side wall, the end wall, or both, to form a cutting port or window end and an elongated inner tubular member concentrically disposed in the outer tubular member and having a distal end disposed adjacent the opening in the distal end of the outer tubular member. The distal end of the inner tubular member has a surface or edge for engaging tissue via the opening in the distal end of the outer tubular member and in many cases cooperates with the opening to shear and cut tissue. The '238 patent goes on to disclose an elongated bearing structure for a surgical cutting instrument having elongated inner and outer tubular members which are said to prevent cocking or skewing of the inner member relative to the outer member without creating galling and possible seizure during operation of the surgical cutting instrument.
In U.S. Pat. No. 5,250,073, there is described a torqueable and formable biopsy forceps. The biopsy forceps are said to provide improved torqueable and formable characteristics. The device includes a handle and core wire connected at its proximal end to the handle and connected at its distal end to a forceps assembly. The control wire displacing device carried by the handle serves to displace the core wire for moving the core wire between a forceps open position and a forceps closed position. The core wire includes at least three elongated portions, including a proximal portion having a proximal end secured to the wire displacing means, a distal portion having a distal end secured to the forceps assembly and an intermediate portion located between the proximal and distal portions. The proximal portion is said to be of greater length than the intermediate or distal portions and of greater diameter than the intermediate portion which, in turn, is said to be of greater diameter than the distal portion.
In U.S. Pat. No. 5,324,301, there is described a surgical instrument comprising inner and outer tubular members with a coating of tin-nickel alloy on the outer surface of the inner tubular member and/or the inner surface of the outer tubular member to provide an elongated bearing surface between the tubular members.
In U.S. Pat. No. 5,322,505, there is described a surgical instrument that includes a rigid outer member within which is disposed a hollow inner member having rigid proximal and distal ends and a region disposed between the rigid proximal and distal ends that is relieved to render such region flexible.
With regards to the above, although various prior art devices have been manufactured, as noted, to improve the performance of surgical instruments for closed surgery procedures, one long-standing problem has emerged which is the tendency of such surgical cutting instruments to rotate in the direction corresponding to the wire wrapping on the surface of the outer jacket. That is, the surgical cutting instruments of the prior art generally have disposed on the outer jacket a wire-wrap with a constant and continuous right or left-hand wrap configuration. As a consequence, upon activation of the control wire displacement means which runs through the inner regions of the outer tubular member, the surgical cutting instrument tends to rotate or torque in the direction of the wrap. Moreover, there is a measured reduction in the force transmitted to the distal end cutting jaws.
Accordingly, in my copending application Ser. No. 08/422,049, it was a primary object of the invention to overcome the various problems and disadvantages associated with surgical cutting instruments of the prior art both which tend to displace from a target location, and sacrifice cutting strength, in a closed surgical procedure. In particular, it was disclosed that one could achieve this objective by providing a surgical cutting instrument which contained an anti-torque outer jacket, which eliminates torque distortion and reduces the loss in force delivered to the distal cutting means.
With respect to the development of the anti-torque outer jacket, as noted above, it became apparent that many of the devices of the prior art, including those devices that did not contain such anti-torque outer jackets, were problematic in their operation, from the point of view of their ease of use, sterilizability and/or ability to be cleaned. That is, the inner control wire of the device, which connected to the cutting means, and which was multi-stranded itself, would necessarily create a small but nevertheless significant region for body fluids or tissue to become fixed after use.
In addition, the control wire means of the prior art would necessarily contact the inner surface of the hollow-body lumen, and when displaced, create some metal-to-metal frictional resistance with said surface of the lumen.
Accordingly, it has become an object of this invention to overcome the above disadvantages associated with the prior art, and provide a control wire means, surrounded with a coating, such that the coating reduces friction as between the control wire means and outer lumen, and in addition, provides a seal as against the uptake of body fluids or small tissue.
In particular, it is an object of this invention to provide a plastic film tubing surrounding the inner control wire means of a surgical cutting instrument, characterized in that the tubing collectively improves the ease of use of the instrument, minimizes contamination, and renders more efficient the reuse, cleaning and/or sterilization procedures.